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[catacomb] / symm / cfb-def.h
1 /* -*-c-*-
2 *
3 * Definitions for ciphertext feedback mode
4 *
5 * (c) 1999 Straylight/Edgeware
6 */
7
8 /*----- Licensing notice --------------------------------------------------*
9 *
10 * This file is part of Catacomb.
11 *
12 * Catacomb is free software; you can redistribute it and/or modify
13 * it under the terms of the GNU Library General Public License as
14 * published by the Free Software Foundation; either version 2 of the
15 * License, or (at your option) any later version.
16 *
17 * Catacomb is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 * GNU Library General Public License for more details.
21 *
22 * You should have received a copy of the GNU Library General Public
23 * License along with Catacomb; if not, write to the Free
24 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
25 * MA 02111-1307, USA.
26 */
27
28 #ifndef CATACOMB_CFB_DEF_H
29 #define CATACOMB_CFB_DEF_H
30
31 #ifdef __cplusplus
32 extern "C" {
33 #endif
34
35 /*----- Header files ------------------------------------------------------*/
36
37 #include <string.h>
38
39 #include <mLib/bits.h>
40 #include <mLib/sub.h>
41
42 #ifndef CATACOMB_ARENA_H
43 # include "arena.h"
44 #endif
45
46 #ifndef CATACOMB_BLKC_H
47 # include "blkc.h"
48 #endif
49
50 #ifndef CATACOMB_GCIPHER_H
51 # include "gcipher.h"
52 #endif
53
54 #ifndef CATACOMB_PARANOIA_H
55 # include "paranoia.h"
56 #endif
57
58 #ifndef CATACOMB_PARANOIA_H
59 # include "paranoia.h"
60 #endif
61
62 /*----- Macros ------------------------------------------------------------*/
63
64 /* --- @CFB_DEF@ --- *
65 *
66 * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher
67 *
68 * Use: Creates an implementation for CFB mode.
69 */
70
71 #define CFB_DEF(PRE, pre) CFB_DEFX(PRE, pre, #pre, #pre)
72
73 #define CFB_DEFX(PRE, pre, name, fname) \
74 \
75 /* --- @pre_cfbgetiv@ --- * \
76 * \
77 * Arguments: @const pre_cfbctx *ctx@ = pointer to CFB context block \
78 * @void *iv@ = pointer to output data block \
79 * \
80 * Returns: --- \
81 * \
82 * Use: Reads the currently set IV. Reading and setting an IV \
83 * is not transparent to the cipher. It will add a `step' \
84 * which must be matched by a similar operation during \
85 * decryption. \
86 */ \
87 \
88 void pre##_cfbgetiv(const pre##_cfbctx *ctx, void *iv) \
89 { \
90 octet *p = iv; \
91 unsigned off = ctx->off; \
92 unsigned rest = PRE##_BLKSZ - off; \
93 \
94 memcpy(p, ctx->b + off, rest); \
95 memcpy(p + rest, ctx->b, off); \
96 } \
97 \
98 /* --- @pre_cfbsetiv@ --- * \
99 * \
100 * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
101 * @cnost void *iv@ = pointer to IV to set \
102 * \
103 * Returns: --- \
104 * \
105 * Use: Sets the IV to use for subsequent encryption. \
106 */ \
107 \
108 void pre##_cfbsetiv(pre##_cfbctx *ctx, const void *iv) \
109 { memcpy(ctx->b, iv, PRE##_BLKSZ); ctx->off = PRE##_BLKSZ; } \
110 \
111 /* --- @pre_cfbbdry@ --- * \
112 * \
113 * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
114 * \
115 * Returns: --- \
116 * \
117 * Use: Inserts a boundary during encryption. Successful \
118 * decryption must place a similar boundary. \
119 */ \
120 \
121 void pre##_cfbbdry(pre##_cfbctx *ctx) \
122 { \
123 uint32 t[PRE##_BLKSZ/4]; \
124 \
125 BLKC_LOAD(PRE, t, ctx->b); \
126 pre##_eblk(&ctx->ctx, t, t); \
127 BLKC_STORE(PRE, ctx->b, t); \
128 ctx->off = PRE##_BLKSZ; \
129 BURN(t); \
130 } \
131 \
132 /* --- @pre_cfbsetkey@ --- * \
133 * \
134 * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
135 * @const pre_ctx *k@ = pointer to cipher context \
136 * \
137 * Returns: --- \
138 * \
139 * Use: Sets the CFB context to use a different cipher key. \
140 */ \
141 \
142 void pre##_cfbsetkey(pre##_cfbctx *ctx, const pre##_ctx *k) \
143 { ctx->ctx = *k; ctx->off = PRE##_BLKSZ; } \
144 \
145 /* --- @pre_cfbinit@ --- * \
146 * \
147 * Arguments: @pre_cfbctx *ctx@ = pointer to cipher context \
148 * @const void *key@ = pointer to the key buffer \
149 * @size_t sz@ = size of the key \
150 * @const void *iv@ = pointer to initialization vector \
151 * \
152 * Returns: --- \
153 * \
154 * Use: Initializes a CFB context ready for use. You should \
155 * ensure that the IV chosen is unique: reusing an IV will \
156 * compromise the security of at least the first block \
157 * encrypted. This is equivalent to calls to @pre_init@, \
158 * @pre_cfbsetkey@ and @pre_cfbsetiv@. \
159 */ \
160 \
161 void pre##_cfbinit(pre##_cfbctx *ctx, \
162 const void *key, size_t sz, \
163 const void *iv) \
164 { \
165 static const octet zero[PRE##_BLKSZ] = { 0 }; \
166 \
167 pre##_init(&ctx->ctx, key, sz); \
168 pre##_cfbsetiv(ctx, iv ? iv : zero); \
169 } \
170 \
171 /* --- @pre_cfbencrypt@ --- * \
172 * \
173 * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
174 * @const void *src@ = pointer to source data \
175 * @void *dest@ = pointer to destination data \
176 * @size_t sz@ = size of block to be encrypted \
177 * \
178 * Returns: --- \
179 * \
180 * Use: Encrypts a block with a block cipher in CFB mode. The \
181 * input block may be arbitrary in size. CFB mode is not \
182 * sensitive to block boundaries. \
183 */ \
184 \
185 void pre##_cfbencrypt(pre##_cfbctx *ctx, \
186 const void *src, void *dest, \
187 size_t sz) \
188 { \
189 const octet *s = src; \
190 octet *d = dest; \
191 unsigned off = ctx->off; \
192 uint32 t[PRE##_BLKSZ/4]; \
193 octet y; \
194 \
195 /* --- Empty blocks are trivial --- */ \
196 \
197 if (!sz) return; \
198 \
199 /* --- If I can deal with the block from my buffer, do that --- */ \
200 \
201 if (sz < PRE##_BLKSZ - off) goto small; \
202 \
203 /* --- Finish off what's left in my buffer --- */ \
204 \
205 while (off < PRE##_BLKSZ) { \
206 y = s ? *s++ : 0; \
207 ctx->b[off] ^= y; \
208 if (d) *d++ = ctx->b[off]; \
209 off++; sz--; \
210 } \
211 \
212 /* --- Main encryption loop --- */ \
213 \
214 BLKC_LOAD(PRE, t, ctx->b); \
215 \
216 for (;;) { \
217 pre##_eblk(&ctx->ctx, t, t); \
218 if (sz < PRE##_BLKSZ) break; \
219 if (s) { BLKC_XLOAD(PRE, t, s); s += PRE##_BLKSZ; } \
220 if (d) { BLKC_STORE(PRE, d, t); d += PRE##_BLKSZ; } \
221 sz -= PRE##_BLKSZ; \
222 } \
223 \
224 BLKC_STORE(PRE, ctx->b, t); \
225 off = 0; \
226 \
227 /* --- Tidying up the tail end --- */ \
228 \
229 if (sz) { \
230 small: \
231 do { \
232 y = s ? *s++ : 0; \
233 ctx->b[off] ^= y; \
234 if (d) *d++ = ctx->b[off]; \
235 off++; sz--; \
236 } while (sz); \
237 } \
238 \
239 /* --- Done --- */ \
240 \
241 ctx->off = off; \
242 return; \
243 } \
244 \
245 /* --- @pre_cfbdecrypt@ --- * \
246 * \
247 * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \
248 * @const void *src@ = pointer to source data \
249 * @void *dest@ = pointer to destination data \
250 * @size_t sz@ = size of block to be encrypted \
251 * \
252 * Returns: --- \
253 * \
254 * Use: Decrypts a block with a block cipher in CFB mode. The \
255 * input block may be arbitrary in size. CFB mode is not \
256 * sensitive to block boundaries. \
257 */ \
258 \
259 void pre##_cfbdecrypt(pre##_cfbctx *ctx, \
260 const void *src, void *dest, \
261 size_t sz) \
262 { \
263 const octet *s = src; \
264 octet *d = dest; \
265 unsigned off = ctx->off; \
266 uint32 t[PRE##_BLKSZ/4], u[PRE##_BLKSZ/4]; \
267 octet y; \
268 \
269 /* --- Empty blocks are trivial --- */ \
270 \
271 if (!sz) return; \
272 \
273 /* --- If I can deal with the block from my buffer, do that --- */ \
274 \
275 if (sz < PRE##_BLKSZ - off) goto small; \
276 \
277 /* --- Finish off what's left in my buffer --- */ \
278 \
279 while (off < PRE##_BLKSZ) \
280 { y = *s++; *d++ = ctx->b[off] ^ y; ctx->b[off++] = y; sz--; } \
281 \
282 /* --- Main encryption loop --- */ \
283 \
284 BLKC_LOAD(PRE, t, ctx->b); \
285 \
286 for (;;) { \
287 pre##_eblk(&ctx->ctx, t, t); \
288 if (sz < PRE##_BLKSZ) break; \
289 BLKC_LOAD(PRE, u, s); s += PRE##_BLKSZ; \
290 BLKC_XSTORE(PRE, d, t, u); d += PRE##_BLKSZ; \
291 BLKC_MOVE(PRE, t, u); \
292 sz -= PRE##_BLKSZ; \
293 } \
294 \
295 BLKC_STORE(PRE, ctx->b, t); \
296 off = 0; \
297 \
298 /* --- Tidying up the tail end --- */ \
299 \
300 if (sz) { \
301 small: \
302 do { y = *s++; *d++ = ctx->b[off] ^ y; ctx->b[off++] = y; sz--; } \
303 while (sz); \
304 } \
305 \
306 /* --- Done --- */ \
307 \
308 ctx->off = off; \
309 return; \
310 } \
311 \
312 /* --- Generic cipher interface --- */ \
313 \
314 static const gcipher_ops gops; \
315 \
316 typedef struct gctx { \
317 gcipher c; \
318 pre##_cfbctx k; \
319 } gctx; \
320 \
321 static gcipher *ginit(const void *k, size_t sz) \
322 { \
323 gctx *g = S_CREATE(gctx); \
324 g->c.ops = &gops; \
325 pre##_cfbinit(&g->k, k, sz, 0); \
326 return (&g->c); \
327 } \
328 \
329 static void gencrypt(gcipher *c, const void *s, void *t, size_t sz) \
330 { gctx *g = (gctx *)c; pre##_cfbencrypt(&g->k, s, t, sz); } \
331 \
332 static void gdecrypt(gcipher *c, const void *s, void *t, size_t sz) \
333 { gctx *g = (gctx *)c; pre##_cfbdecrypt(&g->k, s, t, sz); } \
334 \
335 static void gdestroy(gcipher *c) \
336 { gctx *g = (gctx *)c; BURN(*g); S_DESTROY(g); } \
337 \
338 static void gsetiv(gcipher *c, const void *iv) \
339 { gctx *g = (gctx *)c; pre##_cfbsetiv(&g->k, iv); } \
340 \
341 static void gbdry(gcipher *c) \
342 { gctx *g = (gctx *)c; pre##_cfbbdry(&g->k); } \
343 \
344 static const gcipher_ops gops = { \
345 &pre##_cfb, \
346 gencrypt, gdecrypt, gdestroy, gsetiv, gbdry \
347 }; \
348 \
349 const gccipher pre##_cfb = { \
350 name "-cfb", pre##_keysz, PRE##_BLKSZ, \
351 ginit \
352 }; \
353 \
354 CFB_TESTX(PRE, pre, name, fname)
355
356 /*----- Test rig ----------------------------------------------------------*/
357
358 #define CFB_TEST(PRE, pre) CFB_TESTX(PRE, pre, #pre, #pre)
359
360 #ifdef TEST_RIG
361
362 #include "modes-test.h"
363
364 /* --- @CFB_TEST@ --- *
365 *
366 * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions
367 *
368 * Use: Standard test rig for CFB functions.
369 */
370
371 #define CFB_TESTX(PRE, pre, name, fname) \
372 \
373 static pre##_ctx key; \
374 static pre##_cfbctx ctx; \
375 \
376 static void pre##_cfb_test_setup(const octet *k, size_t ksz) \
377 { pre##_init(&key, k, ksz); pre##_cfbsetkey(&ctx, &key); } \
378 \
379 static void pre##_cfb_test_reset(const octet *iv) \
380 { pre##_cfbsetiv(&ctx, iv); } \
381 \
382 static void pre##_cfb_test_enc(const octet *s, octet *d, size_t sz) \
383 { pre##_cfbencrypt(&ctx, s, d, sz); } \
384 \
385 static void pre##_cfb_test_dec(const octet *s, octet *d, size_t sz) \
386 { pre##_cfbdecrypt(&ctx, s, d, sz); } \
387 \
388 int main(int argc, char *argv[]) \
389 { \
390 return test_encmode(fname "-cfb", PRE##_KEYSZ, PRE##_BLKSZ, 1, 0, \
391 pre##_cfb_test_setup, pre##_cfb_test_reset, \
392 pre##_cfb_test_enc, pre##_cfb_test_dec, \
393 argc, argv); \
394 }
395
396 #else
397 # define CFB_TESTX(PRE, pre, name, fname)
398 #endif
399
400 /*----- That's all, folks -------------------------------------------------*/
401
402 #ifdef __cplusplus
403 }
404 #endif
405
406 #endif
Catacomb cryptographic library